


late-night assistance

by shotacatboy



Category: Shall We Date?: Obey Me!
Genre: Collars, Demoncest, Explicit Sexual Content, Incest, M/M, Mammon is a good bro, Mentioned Character Death, power bottom belphie, slight BDSM, some good old emotional vulnerability
Language: English
Status: Completed
Published: 2020-09-10
Updated: 2020-09-10
Packaged: 2021-03-06 15:35:38
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,133
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26391289
Author URL: https://archiveofourown.org/users/shotacatboy/pseuds/shotacatboy
Summary: He opens his eyes and sees Belphegor straddled above him. His features are pulled tight into a passive expression, the sort he wears when he's up to nothing good.Mammon swallows. "Hey, Belphie," he whispers, "whaddya doin'?"Belphegor's lips twitch with the ghost of a smile. He reaches for the bag he placed aside earlier."I can't sleep," he answers. "Let's try something different."Or: Mammon helps Belphie go back to sleep.
Relationships: Belphegor/Mammon (Shall We Date?: Obey Me!)
Comments: 5
Kudos: 122





	late-night assistance

**Author's Note:**

> threw this together really fast for mammon's birthday bc the other fic i had planned wasn't working out. i hope this is fine regardless!

Mammon expects the knock at his door, just as much as he expects the person knocking to be Belphegor. He also expects the drowsiness tugging at his eyelids, and the slurred, tired way he mutters a greeting, clutching his signature pillow tightly to himself.

What he  _ doesn't  _ expect, however, is the bag Belphegor holds in his free arm. It's small and black and the unseen objects inside click as they smack against each other. The logo printed on the front is one Mammon recognizes but cannot quite place in his shocked stupor—somewhere close, maybe. Somewhere familiar.

Heedless, he's left no room to question it as Belphegor's shoulder bumps his. When Mammon meets his eyes he sees a slight spark behind them, bright with mischief.

_ He's planning something, _ Mammon decides.  _ He definitely is. _

"Are you gonna let me inside?" Belphegor asks. He attempts to step around but Mammon steps with him, effectively blocking him.

"Wait a minute," Mammon says. He points to the bag. "What's that?"

"I'll show you," Belphegor replies, easily enough, "if you'd just let me in your room already. Come on, it's cold out here." He manages a shudder for emphasis.

Mammon, though reluctant, does not refuse. He steps aside and watches cautiously as Belphegor enters his room, raising his arms and yawning loudly.

At his bed, he's surprised to see Belphegor place the bag aside. It lands on his dresser with a soft clack and Belphegor collapses atop the mattress, stretching his limbs out as a means to grow comfortable, tucking his pillow beneath his chin.

Eventually he rolls over and pats the space beside himself.

"Let's go to sleep. We have classes tomorrow, don't we?"

This, Mammon thinks, is more familiar, and he nods as he climbs in bed beside him.

***

It's impossible to tell what Belphegor is thinking.

Ever since his departure from the attic, things have been… different.

The tension that hangs in the air is terse, thick, like a knife meeting the edge of solid butter. Against the promise for a better future there remain stolen glances and awkward silences whenever Belphegor happens to inhabit a room, whispered words among their brothers when they think Belphegor can't hear and half-assed excuses to get away—and it doesn't take a genius to understand why.

He killed someone. He killed the human. Mammon knows it well, remembers it in the way their lifeless body had felt clutched in his arms and the scathing, brutal marks that were left around their throat, burning red; as well as their hazed, lifeless eyes, bearing a gaze leading to nowhere…

Now, despite the way things have turned out, Mammon isn't sure how to speak to Belphegor.

He's unable, expectedly, to rid the scent of blood from his nose, or the memory of how it had stained his hands and his clothes. The smile Belphegor held that day also remains etched in the far corners of his mind, bright and baring fangs as he laughed at the situation he'd caused.

It's hard to decide how he feels. He cannot be angry—or, at the very least, not entirely. Not with the way Belphegor curls against his chest and furrows his brows as he sleeps, face contorted in visible pain.

_ Or is it regret? _ Mammon wonders. He brushes a thumb against Belphegor's cheek and lets out a breath as his wrist is caught, hand tugged forward and tucked beneath Belphegor's chin as a means to bring him closer. His skin is warm.

It's been like this for several weeks, already. Belphegor demanding entrance to his room late at night, taking position on his bed beside him and falling asleep almost instantly.

On some nights, he's silent, motionless. On others, like tonight, he stirs, groans, tossing and turning and muttering nonsense Mammon is unable to decipher. He assumes this must be caused by nightmares.

_ But why here?  _ Mammon thinks.  _ Is he tryna make fun of me? _

He doubts it. If this was a joke on his part Belphegor would've revealed his intentions by now, wouldn't he? Were there malice behind his actions, additionally, why would he allow himself to be seen in such a vulnerable position, with his agony on full display and tears catching the corners of his eyes?

No. There's something else. Something Belphegor isn't telling him.

Mammon huffs.  _ Maybe he's just too scared to admit he needs his big brother.  _ Oddly, in spite of the circumstances, he finds the idea rather appealing.  _ Yeah, that's it! Well, that's fine, I guess. Since he 'n Beel have been avoiding each other I s'ppose he  _ would  _ need someone. _

A pang of sympathy swells his chest and he nods, suddenly determined.  _ Fine, then. I'll make sure t' comfort him like he's never been comforted before! _

At that, he falls asleep. He isn't sure when, but when he wakes there is a heavy weight rested on his abdomen, thin fingers threaded in his hair.

He opens his eyes and sees Belphegor straddled above him. His features are pulled tight into a passive expression, the sort he wears when he's up to nothing good.

Mammon swallows. "Hey, Belphie," he whispers, "whaddya doin'?"

Belphegor's lips twitch with the ghost of a smile. He reaches for the bag he placed aside earlier.

"I can't sleep," he answers. "Let's try something different."

***

_ Yeah,  _ Mammon concludes, shirtless, with his wrists bound to the headboard,  _ I  _ really  _ can't tell what he thinkin'. _

What last he expected for Belphegor to procure from the bag, surely, were  _ toys _ —several of them, at that, including the handcuffs currently suspending his arms above his head, and the clamps he dangles before Mammon’s face like this is a game, and Mammon’s present state of arousal and befuddlement is something funny to him.

Knowing Belphegor, the prospect isn’t completely illogical.

“I’m so glad I remembered you’re a masochist,” he says, and the way his voice lifts in amusement confirms Mammon’s previous suspicions. Seated in his lap, he moves to close one of the clamps around his nipple.

Mammon’s response is immediate. He bites his lip to stifle a moan as his hips jut forward, growing erection becoming uncomfortably tight in his slacks. Suddenly he wishes he hadn’t been courteous enough to have worn his clothes while sharing his bed with Belphegor, wanting nothing more than for his cock to be free, and to bring himself his due release—

“Hey.”

Belphegor twists the clamp. Mammon lets out a cry at the tightened pressure, painful but pleasurable, addicting. He thinks briefly that this is not so different from Lucifer’s punishments, though it  _ is  _ much less severe is intensity. Belphegor’s shaking hands, as well, give away his inexperience.

It’s this musing that fuels his next words, hissed out through gritted teeth. “I-is that… is that all you got?”

Belphegor hums, lists his head in consideration. The second clamp comes around Mammon’s other nipple and his lower stomach stirs in rising provocation.  _ Damn… He just doesn’t give up. _

“Yeesh,” Belphegor mutters. He shakes his head in what Mammon interprets as thinly-veiled disappointment. “Y’know, I was expecting more of a reaction from you. I’m starting to get a little sad.” He twists both the clamps this time and Mammon moans, louder than he feels happy admitting. “Better, but not good enough.”

“Y-you’re gonna have t’ put in a lot more effort if ya wanna make  _ me  _ break.”

Belphegor rolls his eyes. “Yeah, yeah, let me guess. ‘You’ll never be as good at fucking me as Lucifer.’ Is that what you’re thinking?” He leans forward. Mammon flinches as his lips brush over his cheek.

“Well, that’s—”

“I’m not trying to  _ outdo  _ him,” Belphegor tells him, mouth sliding to nip beneath his chin now, slow and calculated in its movements. Mammon finds the sensation foreign but not unenjoyable.

“Then what’re you  _ trying  _ t’ do?”

“Isn’t it obvious?” Belphegor asks. Mammon shakes his head, confused, and he takes the opportunity to nip at his earlobe. “I’m trying to make you feel  _ good,  _ idiot.”

“O-oh.”

Against his better judgement, he glances downward. Notices Belphegor’s own erection, ever perceptible through the fabric of his pants. He bites his lower lip, deep in concentration.

“D-do ya need help with that?” he asks, albeit shakily.

Belphegor’s reply comes via another harsh twist. Mammon cries out, the sound echoing throughout the expanse of his spacious room.

“I’m fine,” he answers, after a moment. “I’m sure you’ll help me in a little while.”

He doesn’t relent. He twirls the clamps again. And again. Each tug and turn becomes more brutal than the last, beautifully merciless until the coil in Mammon’s abdomen tightens nearly to a breaking point. His wings materialize and flap desperately through the cold night air as he grows closer,  _ closer, _ until at last he cums untouched, still clothed from the waist down.

_ Gross.  _ He shudders at the sticky sensation in his pants as Belphegor removes the clamps, bends and presses a kiss to one of his abused nipples.

“Honestly,” he titters, “I have  _ no  _ idea how you’re into that.”

Mammon huffs, attempting and failing to gather his senses. Blurred dots gather at the edge of his vision.

“Hey,” Belphegor drawls. The sound draws Mammon back to himself. “Are you listening?”

Mammon drops his gaze to meet Belphegor’s, a vivid indigo flashing even in the darkness. It takes a while until he manages to process the question.

“Huh?” he says, stupidly.

Belphegor’s head drops to his shoulder. He begins shaking, which Mammon realizes after a moment is due to restrained laughter.

“I  _ said,”  _ Belphegor repeats, “we aren’t done here yet.” His breath tickles the skin of Mammon’s neck, where he plants several more soft, swift kisses, causing a pleasant buzz to thrum at the very core of his being. “I wanna see how long it takes until I’m tired again.”

Mammon nods, probably a bit too swiftly. Belphegor places the clamps aside and plants his hands on Mammon’s stomach, ghosting along his abdomen, and he instinctively leans into the touch.  _ Warm,  _ he thinks.  _ Everything about him is warm. _

Belphegor’s hand slides to his cheek, gentle in the course it takes and even more so as it moves to his hair next, threading carefully into the white strands and bringing him forward and— Ah. Belphegor is  _ kissing  _ him.

His kisses are everything Mammon expects. Slow, drawn out, lips moving almost lazily against his. Mammon welcomes the tongue that pushes into his mouth and meets it with his own, relishing the small, delighted hum it elicits from Belphegor.

Belphegor pulls away first. He ducks his head quickly, but it isn’t fast enough for Mammon not to observe the slight blush dusting his cheeks.

“What do you wanna do next?” he asks, rummaging through the bag again. Mammon is inexorably drawn to staring at his Adam’s apple as he swallows, slick with sweat he would lick away were he not presently handcuffed to his bed.

“Well?” Belphegor presses, and Mammon registers that the question was not intended to be rhetorical.

“I-I dunno,” he stammers, as he attempts to lean forward to see what’s inside. It’s hard to think when he’s so hard it aches. “Whaddya have?”

Belphegor hums, again. The smile that curves on his lips is damn near intimidating. Mischievous.

“What about this, then?” he asks. When he lifts his hand Mammon sees him holding a collar with an o-ring, letting the latter slip over his index finger in a way curious but undoubtedly taunting. “Or are you too scared?”

Mammon sputters at the sight of it, transfixed on the smooth, black leather, the bright silver of the ring as it reflects off what little light exists in the room.

It isn’t that he isn’t  _ against  _ it, per se, but…

“How did you get that?” He means for it to come out as a demand but the subtle rise in his voice gives away his uncertainty. This is more along the lines of something a certain  _ other  _ brother would use, something meant to brand and shame—and, oddly, the thought turns Mammon on more than anything else has tonight.

Belphegor’s face doesn’t change. He lists his head, appearing as unaffected as ever.  _ Confident,  _ even.

“Wouldn’t you like to know?”

Mammon’s half-tempted to rebuttal his smart-mouthed reply with one of his own, but pauses, reconsiders given the circumstances of what brought them to this point. He doubts a petty argument is what Belphegor needs right now.

Either way, his snark is rather  _ cute,  _ in a way. Enough that Mammon nods and musters a grin, tilting his head to expose his neck in a submissive manner.

“Go ahead,” he says. “Collar me up.”

Belphegor blinks in surprise, clearly having expected a different answer. Regardless he leans forward to slide the collar into place, slipping the leather delicately over Mammon’s throat and clicking the metal pieces into place. He pulls it tight, but not enough to completely restrict Mammon’s airways.

He curves a finger into the o-ring and drags it forward, bringing Mammon’s head closer. The handcuffs sink into his skin from where his wrists remain constrained.

Childishly, Belphegor bites his nose. “Let’s see if you’re as good as you always say you are.”

Mammon isn’t given ample time to inquire as to what that might mean, and is swiftly given his answer in the form of the bottle of lube Belphegor grabs from the bag, put aside for a moment as he tugs his hoodie over his head and removes his slacks, tossing them aside until he’s left in naught but his thin shirt.

Mammon watches, perplexed, as Belphegor leans back and inserts a slicked finger into himself, working it in to the knuckle and moaning softly as he begins a slow stretch. He grins when he spots Mammon’s expression.

“Like the view?” he teases. Mammon stumbles over a reply and he laughs, clearly unbothered by Mammon’s evident desire. “Good. It wouldn’t be fun if you weren’t enjoying it.”

_ “Belphie…” _

“You  _ are  _ enjoying it,” Belphegor interrupts, “aren’t you?” He breaches with a second finger and flinches just momentarily, assuming scissoring motions and biting his bottom lip in a clear show of seduction.

It’s effective. Mammon strains against his binds, wanting, more than anything, to replace those fingers with his, working him open roughly and wiping that stupid, adorable smirk from his face—listening to his broken cries as he falls apart on his digits and then his cock, unable to help his noises admist the perfectly gratifying treatment.

Mammon snaps himself from the mental image without knowing how he’d fallen into it, and instead focuses his attention once more on the display before him. Belphegor manages a third finger and continues for a minute more until he stops altogether, removing them in favor of undoing Mammon’s belt and abruptly yanking it from its loops.

_ Finally,  _ Mammon thinks, as Belphegor pulls his weeping dick free and strokes him once, twice, sneering while he shivers and grunts at the attention. Mammon dislikes how close he is, again, dislikes how much Belphegor’s sniding behavior only arouses him more.

“Are you ready?” Belphegor’s smile indicates this is not a question but a gibe, meant to invoke a reaction. And Mammon, despite his inhibitions, cannot help the way his shoulders quake as he promptly falls for it, too desperate and too horny to care.

“Yes!  _ Fuck!”  _ he hisses, lost in the enveloping warmth that results from Belphegor lowering himself onto him, resisting the urge to release right then and there. No, Belphegor would never let him live  _ that  _ down.

Belphegor laughs, though breathlessly, and grabs hold of Mammon’s horns for leverage as he sinks around his cock further still.

“Oh, older brother,” he moans, dramatically, letting his amusement be apparent in the laugh that punctuates his words, “you’re  _ so  _ big,  _ so  _ tight around me. You really  _ are  _ amazing.”

Mammon would silence him were he in the right headspace. But at present he can’t process anything beyond the heat that surrounds him, or the sweat that sticks to his skin and slides between them, becoming further intensified as Belphegor presses closer,  _ tighter,  _ lifts himself up and drops back down.

_ Damn it!  _ Mammon tenses against the handcuffs yet again and hardly notices the loud snap that resounds from the motion, only processing its meaning once his hands have landed on Belphegor’s waist and Belphegor stares at him, wide-eyed and dazed.

“You  _ broke  _ them,” he says. He does not sound angry, nonetheless. More baffled. Disbelieving.

Mammon chuckles. He lifts Belphegor and pulls him down onto him, harshly. Belphegor’s ensuing whine is like music to his ears.

“Good,” he replies. “Now let’s do this right.”

Belphegor scowls but pulls on the collar and matches his pace, lets Mammon fuck up into him again and again, uttering the occasional cry of his name and shuddering around him in a way Mammon finds mesmorizing. He marvels fleetingly over Belphegor’s features contorted in pleasure, pondering in what ways he might tease him over this later.

But the thought hardly lasts. His orgasm grows ever closer and all it takes is Belphegor spasming as he cums between them for him to careen over the edge, as well, increasing the volume of his thrusts to something wildly frantic before he’s cumming a second time, spilling inside Belphegor and sinking straight teeth into his throat in the aftermath.

It doesn’t dawn on him just how hard he’s bitten until Belphegor’s pushing at his shoulder.  _ “Stop,”  _ he mutters. “I’m bleeding.”

Mammon pulls his teeth away. Sure enough, Belphegor is right. The bruise on his throat oozes blood and Mammon licks it up before he can think better of it, letting his tongue soothe over the wound. Then, satisfied, he lifts Belphegor off him and lowers him onto the mattress.

Mammon is removing the broken handcuffs when he hears Belphegor groan. “That didn’t turn out how I wanted it to at all.”

Mammon sniggers as he settles in next to him. Freshly exhausted, he drags the blanket over them both. “Yeah,” he says, “because it was even  _ better  _ than you expected, huh?”

“Hm,” Belphegor murmurs, in a way indicative of neither affirmation nor refutation. His eyes slide shut and he falls asleep near instantaneously, looking more peaceful than Mammon has seen him in the weeks since they began sharing his room.

Mammon glides his fingers through his hair. He decides, resolutely, if this is what it will take for Belphegor to find some peace at night, he doesn’t mind it.

_ Big brothers are s’pposed to help, anyway,  _ he surmises, satisfied, as he closes his eyes and allows sleep to overcome him.

Come morning, Mammon realizes he'd neglected to remove the collar during the previous evening's haste. Belphegor's responding laugh is chortling, loud, and surprisingly  _ genuine _ —probably the first display of sheer joy Mammon has witnessed from him in a long time.

**Author's Note:**

> i hope u enjoyed! comments and kudos make my day <3
> 
> im also on [twitter](https://twitter.com/shotacatboy) if you wanna talk!


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